Pulse Induction Metal Detector

Pulse induction metal detectors are different from other types of detectors. They use a single coil as receiver and transmitter, and it sends bursts of current through the coil into the ground at the potential target. This bursts lasts milliseconds and then repeats. These PI metal detectors are ideal for finding gold and for use in salty water on the beach. These machines are not good at discrimination but more useful than VLF machines in trashy soil.

Most metal detectors operate by using Very Low Frequency technology. Basically, this means that these detectors have two coils – one to transmit electricity and the other to receive it as it bounces back from objects buried deep in the ground. Pulse induction (PI) metal detectors are less common, but they are quickly becoming more popular.

How does a Pulse Induction Metal Detectors Work?

Pulse Induction metal detectors work by sending a high amperage signal through a, usually, copper coil to create an electromagnetic field. This electromagnetic field is then allowed to collapse which in turn creates a voltage spike that is able to be detected by the receive coil.

If the electromagnetic field is in contact with a metallic object then the voltage spike is affected. This happens because the metallic object stores a small amount of the energy from the electromagnetic field within itself in the form of eddy currents.

PI metal detectors sometimes use one coil to transmit and receive, sometimes have two or three coils that work together. Nevertheless, the detector delivers a short pulse of current into the coil(s) which causes a magnetic field to emanate from the detector coil(s) into the ground. When this short pulse shuts off, the transmitted magnetic field quickly collapses. This collapse creates a return current (back-emf) in the coil as a “reflected” pulse.” This whole process repeats itself hundreds of time a second.

Assuming there is no target in the transmitted magnetic field, a sort of steady-state relationship exists between the duration of sent and received pulses.

However, if there’s a target in the ground, the transmitted pulse creates an opposing magnetic field (eddy current) in the object. When the transmitted pulse’s magnetic field collapses (resulting in the reflected pulse), the opposing magnetic field of the target object makes the reflected pulse take longer to completely disappear. So the detector sees it as a longer-duration reflected pulse than usual.

During each repeated pulse cycle, this time difference is measured by the metal detector’s circuitry, compared to the steady state “expected length”, and a target alert occurs when the difference meets specified thresholds.

Pulse induction metal detector can detect both non-ferrous and ferrous metal objects. At the same time, it won’t pick up the minerals that are in the environment.

Whеrе tо uѕе a Рulѕе Іnduсtіоn metal detector?

Pulse Induction mеtаl dеtесtоrѕ реrfоrm ехtrеmеlу wеll іn hіghlу-mіnеrаlіzеd ѕоіlѕ, thеу’rе еѕѕеntіаllу іmmunе tо іt whіlе mаіntаіnіng hіgh ѕеnѕіtіvіtу.Тhеу саn bе uѕеful іn аnd аrоund:

– Маgnеtіtе hоtrосkѕ (hіgh іrоn соntеnt)
– Ѕаltwаtеr
– Drу аnd wеt blасk ѕаnd
– Соrаl
– Beach
– Shallow waters

What can pulse induction detector finds?

The pulse Induction metal detector is the best metal detector for finding gold because:

PI Detectors do not respond to the iron mineralization.
This is strongly evident in magnetite hotrock conditions which will cause the VLF to overload but not impact on a PI. A nugget of gold next to a magnetite hotrock will be missed by a VLF detector but the positive gold response will be picked up by a PI detectors.
They have increased depth over VLF due to the increased power that can be generated to the coil which creates a stronger signal.